Unauthorized reading of card data, such as data encoded on a magnetic stripe card, while the card is being used (hereafter “card skimming”), is a known type of fraud. Card skimming is typically perpetrated by a fraudster adding a magnetic read head (hereafter “alien reader”) to a fascia of an automated teller machine (ATM) to read a magnetic stripe on a customer's card as the customer inserts or (more commonly) retrieves the card from an ATM. The customer's personal identification number (PIN) is also ascertained by the fraudster when the customer uses the ATM. Examples of how the fraudster ascertains the PIN include: a video camera that captures images of the PINpad on the ATM, a false PINpad overlay that captures the customer's PIN, or the fraudster watching the customer (“shoulder surfing”) as he/she enters his/her PIN. The fraudster can then create a card using the card data read by the alien reader, and can withdraw funds from the customer's account using the created card and the customer's PIN (ascertained by one of the ways described above).
Various methods have been proposed to defeat this type of fraud. One method involves transmitting an electromagnetic signal (hereafter a “jamming signal”) when the card is being transported so that the alien reader cannot detect the magnetically encoded data because of the presence of the jamming signal. Although this technique can be effective, it has some disadvantages.
Card readers typically include a pre-read head that is used to ensure that the customer's card is correctly oriented on insertion. If the pre-read head detects a magnetic stripe, and a width switch detects that the inserted card is the correct width, then a shutter is opened to allow the inserted card to enter into an enclosed card reading chamber. One problem with using a jamming signal is that the jamming signal can overpower (or swamp) the pre-read head so that the pre-read head cannot detect any magnetic stripe. This means that the shutter will not be opened.
One option would be to turn on the jamming signal only after the pre-read head has detected a magnetic stripe. The disadvantage with this approach is that an alien reader may already have read the magnetic stripe by the time the jamming signal has been turned on.
It would be advantageous to be able to use the pre-read head to detect correct orientation of a card, without increasing the risk of skimming of the magnetic data from the inserted card.